The invention rela1es to a tomographic x-ray apparatus for producing transverse layer images of a radiographic subject with an x-ray measuring arrangement comprising an x-ray source producing a beam of x-rays penetrating the radiographic subject of which the cross-sectional extent perpendicular to the layer plane is equal to the layer thickness, and a radiation receiver which determines the intensity of radiation behind the subject, with a drive system for the measuring arrangement including a pivot mounting to produce rotational movements about a longitudinal axis running perpendicularly to the layer plane, a measured value converter for transforming the signals supplied by the radiation receiver into a layer image, and cables which join the measuring arrangement to an x-ray generator and the measured value converter.
A tomographic apparatus of this type is described in U.S. Pat. No. 3,778,614. In order to determine the layer image, the rotational movements may be made in small equidistant angular increments in alternating sequence with one linear scanning displacement each time, of the measuring arrangement along a straight line perpendicular to the central ray of the x-ray beam, if a single radiation detector is used as the radiation receiver. However, it is also a known fact that these linear scanning displacements are unnecessary if the radiation receiver is made up of a plurality of radiation detectors whose signals are processed simultaneously by the measured value converter, and if the x-ray beam is fan-shaped and impinges upon all the detectors simultaneously. In this case, a good image may be produced if the measuring arrangement is rotated about the patient through an angle of 380.degree. during a measurement operation. The problem here is to run the cables for the measuring arrangement such that this rotation can proceed without disruption.